/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.api.java.typeutils;

import org.apache.flink.annotation.Public;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.common.functions.InvalidTypesException;
import org.apache.flink.api.common.typeinfo.AtomicType;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.common.typeutils.TypeComparator;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.java.typeutils.runtime.WritableComparator;
import org.apache.flink.api.java.typeutils.runtime.WritableSerializer;

import org.apache.hadoop.io.Writable;

import static org.apache.flink.util.Preconditions.checkArgument;
import static org.apache.flink.util.Preconditions.checkNotNull;

/**
 * Type information for data types that extend Hadoop's {@link Writable} interface. The Writable
 * interface defines the serialization and deserialization routines for the data type.
 *
 * @param <T> The type of the class represented by this type information.
 */
@Public
public class WritableTypeInfo<T extends Writable> extends TypeInformation<T>
        implements AtomicType<T> {

    private static final long serialVersionUID = 1L;

    private final Class<T> typeClass;

    @PublicEvolving
    public WritableTypeInfo(Class<T> typeClass) {
        this.typeClass = checkNotNull(typeClass);

        checkArgument(
                Writable.class.isAssignableFrom(typeClass) && !typeClass.equals(Writable.class),
                "WritableTypeInfo can only be used for subclasses of %s",
                Writable.class.getName());
    }

    @SuppressWarnings({"rawtypes", "unchecked"})
    @Override
    @PublicEvolving
    public TypeComparator<T> createComparator(
            boolean sortOrderAscending, ExecutionConfig executionConfig) {
        if (Comparable.class.isAssignableFrom(typeClass)) {
            return new WritableComparator(sortOrderAscending, typeClass);
        } else {
            throw new UnsupportedOperationException(
                    "Cannot create Comparator for "
                            + typeClass.getCanonicalName()
                            + ". "
                            + "Class does not implement Comparable interface.");
        }
    }

    @Override
    @PublicEvolving
    public boolean isBasicType() {
        return false;
    }

    @Override
    @PublicEvolving
    public boolean isTupleType() {
        return false;
    }

    @Override
    @PublicEvolving
    public int getArity() {
        return 1;
    }

    @Override
    @PublicEvolving
    public int getTotalFields() {
        return 1;
    }

    @Override
    @PublicEvolving
    public Class<T> getTypeClass() {
        return this.typeClass;
    }

    @Override
    @PublicEvolving
    public boolean isKeyType() {
        return Comparable.class.isAssignableFrom(typeClass);
    }

    @Override
    @PublicEvolving
    public TypeSerializer<T> createSerializer(ExecutionConfig executionConfig) {
        return new WritableSerializer<T>(typeClass);
    }

    @Override
    public String toString() {
        return "WritableType<" + typeClass.getName() + ">";
    }

    @Override
    public int hashCode() {
        return typeClass.hashCode();
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof WritableTypeInfo) {
            @SuppressWarnings("unchecked")
            WritableTypeInfo<T> writableTypeInfo = (WritableTypeInfo<T>) obj;

            return writableTypeInfo.canEqual(this) && typeClass == writableTypeInfo.typeClass;

        } else {
            return false;
        }
    }

    @Override
    public boolean canEqual(Object obj) {
        return obj instanceof WritableTypeInfo;
    }

    // --------------------------------------------------------------------------------------------

    @PublicEvolving
    static <T extends Writable> TypeInformation<T> getWritableTypeInfo(Class<T> typeClass) {
        if (Writable.class.isAssignableFrom(typeClass) && !typeClass.equals(Writable.class)) {
            return new WritableTypeInfo<T>(typeClass);
        } else {
            throw new InvalidTypesException(
                    "The given class is no subclass of " + Writable.class.getName());
        }
    }
}
